In the practice of medical diagnostics, it is often necessary to perform a biopsy to remove a sample of a patient's tissue or fluid for pathological study. For example, biopsies can be useful in diagnosing various forms of cancer and other diseases affecting a localized area of tissue. Biopsy procedures may be used to take tissue and/or fluid samples from muscles, bones and organs, such as the liver or lungs. In some instances, a biopsy sample may be obtained by invasive surgical procedures. However, minimally invasive biopsy procedures are often preferred, such as fine needle aspiration and fine needle biopsy because such procedures are less traumatic to the patient.
Both fine needle aspiration (FNA) and fine needle biopsy (FNB) procedures rely on a needle for collecting the target sample. Biopsy needles are generally classified as being either an end cutting needle or a side cutting needle. An end cutting needle generally includes a hollow cannula having a beveled, circumferentially sharpened, open end at its distal portion. A stylet may be inserted into the hollow shaft of the cannula and extend flush with the open cutting edge of the cannula to close the open end. When the biopsy needle is inserted, the stylet generally functions to puncture the target site (e.g., tissue mass) where the biopsy specimen is to be taken. The stylet is then withdrawn and the cannula further inserted into the tissue mass, wherein the sharpened and beveled leading end is configured to cut tissue and collect the cut tissue into the open distal end of the cannula. A suction device may be applied to a proximal portion of the cannula so as to draw the tissue into the lumen of the cannula.
Generally, the goal of FNA and/or FNB is to acquire sufficient tissue to allow a diagnosis to be made. Currently, different needle configurations are used to collect different sample types (e.g., intact multi-cell samples useful for histology, cells and fragments useful for cytology, etc.). However, many existing biopsy needles are inefficient when collecting samples. For example, with respect to end cutting needles, some current needle tip designs generally result in tearing of target tissue, which may result in a less than ideal core sample and unnecessary trauma to the surrounding tissue, which may cause further complications to the patient (e.g., internal bleeding, bruising, etc.) requiring further treatment. Side cutting needles suffer from the drawback of not effectively drawing a tissue sample of sufficient size into the notch on the cannula. Accordingly, samples extracted by such biopsy needles may not provide sufficient tissue to perform an adequate examination and thus frequently require additional biopsies to be taken. Additionally, such needles suffer from the disadvantage of having to be advanced into the desired tissue site such that the needle may possibly extend beyond the tissue site, thus resulting in the recovery of an inaccurate or non-usable tissue sample, or even resulting in injury to adjacent organs or structures due to such overpenetration.
Additionally, some needles that obtain a full cylinder or “full core” of tissue have difficulty in withdrawing tissue and/or in maintaining the physical state of the tissue so as to provide an accurate assessment of tissue morphology. For example, some needles rely on scoring and/or mashing techniques during tissue collection, which may result in a damaged tissue sample. Depending on the diagnostics, physical characteristics of tissue, such as placement or orientation of cells or tissue, may be as important, or more important, than the chemical or biological characteristics (e.g. presence of malignant cells or by-products).
Furthermore, current needle tip designs may be insufficient for biopsy of certain types of tissue. For example, some lesions are particularly fibrous (e.g., pancreatic lesions) and are difficult to penetrate. Some bevel designs, such as the standard beveled cutting end of needle 100, may initially pierce a portion of the target lesion, but may then deflect off of, or drift, from the target lesion due to the inadequate tip design and/or inability to fully penetrate the lesion, which results in a poor tissue sample, and may even lead to damage to surrounding tissues or vital organs. Additionally, current bevel designs may merely shear off a portion of the target tissue and fail to collect some, or even all, of the sampled tissue within the lumen of the needle due to inadequate tip design.